40 replies to this topic

[martinf]

Hi all,

I'm planning to do the 'Pipo' exhaust mod on my otherwise standard 2.2 NA. I'm also wondering whether I should also cut out the precat.

 

Could someone give me their thoughts please regarding the precat removal, both postive and negative.

 

I'm particularly interested to know:

1. Will it make passing the MOT tricky?
2. Will it make the exhaust noise any louder (especially with the Pipo mod) ?
3. Will it improve the power/torque ?

Thanks.

 

[smiley]

1. No none whatsoever. This has been done by the hundreds.
2. The main purpose is to relieve the maifold a little. The precat removal should not make any difference in sound. Only the pipomod does that.
3. None whatsoever. It's a bit like that playingcard you put on your bikewheel when you were 8, but the grownup version.

 

[paul_mck]

is there not a measurable benefit to removing it? else whats the point?

[smiley]

broem broem

[martinf]

1. No none whatsoever. This has been done by the hundreds.
2. The main purpose is to relieve the maifold a little. The precat removal should not make any difference in sound. Only the pipomod does that.
3. None whatsoever. It's a bit like that playingcard you put on your bikewheel when you were 8, but the grownup version.

 

That's spooky, I did the bikewheel mod too - last week

 

As paul_mck said - surely there must be some advantage, otherwise why do it?

[paul_mck]

maybe its more a supporting mod for 2.4 inlet and cams etc. Thats why I did mine, in conjunction with some other things. Dont think its worth the effort unless its coming off anyway.

[Lee37vernon]

My cast manifold was changed last week due to a crack, in process I discovered my cat has had its innards totally removed. Doesn't seem too noisy and runs fine.. Went through MOT last time like it

[ayresyy]

  I have only recently carried out a pre-cat removal on an N/A. After driving before and after you do notice a (very slight) improvement in power. It's maybe only 2-3 BHP, but its a free mod and could well prolong the life of the OE manifold if yours is still crack free.  

[martinf]

Thanks guys, Nobody has said anything negative about removing it, and it seems it might help, so I'm going to remove it at the same time as doing the Pipo back box mod.. Thanks for taking the time to give me your views.

[sford]

The main benefit will be that it removes the heat build up point right after the manifold and hopefully prevent it cracking. I did mine when I changed the manifold due to the crack. It made no difference to the car at the time other than the slight weight saving. About 5 years later when I went SC I noticed the manifold had cracked again although I imagine that the one I had replaced it with had probably spent most of it's life behind a precat too. 

 

If you are taking the car apart and access is easy, then do it. I wouldn't do the one mod on it's own, more combine it with a few other jobs. 

[martinf]

Thanks, I'm just about to start the 'Pipo' mod, so it's easy to do the precat removal as well. thanks for your comments. Martin.

[The Batman]

quickest pre cat i did was 23 seconds

 

feel free to try and beat me!

[aquilaproejct]

WOT s/C running super rich? 😁

[oakmere]

I felt a difference after precat removal. not huge but noticeable with improved throttle response.

[oakmere]

I felt a difference after precat removal. not huge but noticeable with improved throttle response.

[martinf]

Removed the precat yesterday, what a stubborn little jigger. Took me about 2 hours I reckon, polished the inside of the pipe for good measure.

Now working on the back box

Sent from my LG-H990 using Tapatalk

[ayresyy]

  I used a cobalt drill bit to drill around the edges and a pint of water for cooling the drill bit in. Didn't want to risk cutting fluid/oil etc getting into the main cat.

 

Took about 30 mins to remove that way, but they can be stubborn to get out if the car is lowish millage and fairly standard as they haven't been 'softened up' much!

[blackoctagon]

I'd do it for the weight savings.
Must be at least 80g just bogging you down there.

[martinf]

Well, th precat is all done and the Pipo exhaust mod completed too. Since the clam is off I can't drive it, but the sound from the exhaust seems exactly the same to me.

 

[smiley]

I believe the pipo mod is percieved as subtle on blast, so give it a try asap.

If you still have the oem airbox, an open cone will also make it sound more alive.